$(document).ready(function () {
   
           
    
    redrawDotNav();

    /* Scroll event handler */
    $(window).bind('scroll', function (e) {
        parallaxScroll();
        redrawDotNav();
    });

    /* Next/prev and primary nav btn click handlers  -------Truoc silde theo thoi gian -----------*/
    $('a.manned-flight').click(function () {
        $('html, body').animate({
            scrollTop: 0
        }, 1000, function () {
            parallaxScroll(); // Callback is required for iOS
        });
        return false;
    });
    $('a.frameless-parachute').click(function () {
        $('html, body').animate({
            scrollTop: $('#frameless-parachute').offset().top
        }, 1000/*Thoi gian scroll*/, function () {
            parallaxScroll(); // Callback is required for iOS
        });
        return false;
    });
    $('a.english-channel').click(function () {
        $('html, body').animate({
            scrollTop: $('#english-channel').offset().top
        }, 1000, function () {
            parallaxScroll(); // Callback is required for iOS
        });
        return false;
    });
    $('a.about').click(function () {
        $('html, body').animate({
            scrollTop: $('#about').offset().top
        }, 1000, function () {
            parallaxScroll(); // Callback is required for iOS
        });
        return false;
    });

    /* Show/hide dot lav labels on hover  ----- show tooltip -----------*/
    $('nav#primary a').hover(
    	function () {
    	    $(this).prev('h1').show();
    	},
		function () {
		    $(this).prev('h1').hide();
		}
    );

});

/* Scroll the background layers */
function parallaxScroll() {
    var scrolled = $(window).scrollTop();
    $('#parallax-bg1').css('top', (0 - (scrolled * .25)) + 'px');
    $('#parallax-bg2').css('top', (0 - (scrolled * .5)) + 'px');
    $('#parallax-bg3').css('top', (0 - (scrolled * .75)) + 'px');
}

/* Set navigation dots to an active state as the user scrolls */
function redrawDotNav() {
    var section1Top = 0;
    // The top of each section is offset by half the distance to the previous section.
    var section2Top = $('#frameless-parachute').offset().top - (($('#english-channel').offset().top - $('#frameless-parachute').offset().top) / 2);
    var section3Top = $('#english-channel').offset().top - (($('#about').offset().top - $('#english-channel').offset().top) / 2);
    var section4Top = $('#about').offset().top - (($(document).height() - $('#about').offset().top) / 2);
    $('nav#primary a').removeClass('active');
    if ($(document).scrollTop() >= section1Top && $(document).scrollTop() < section2Top) {
        $('nav#primary a.manned-flight').addClass('active');
    } else if ($(document).scrollTop() >= section2Top && $(document).scrollTop() < section3Top) {
        $('nav#primary a.frameless-parachute').addClass('active');
    } else if ($(document).scrollTop() >= section3Top && $(document).scrollTop() < section4Top) {
        $('nav#primary a.english-channel').addClass('active');
    } else if ($(document).scrollTop() >= section4Top) {
        $('nav#primary a.about').addClass('active');
    }

}
